Well first of all, be sure they diagnosed him with cystic fibrosis before you jump ahead. A 77 year old being diagnosed, while not impossible, would be very rare. CF is genetic, and most people are diagnosed in early childhood. Those that aren't are diagnosed in early/mid adulthood. Being diagnosed as late as 77 would be very bizarre. Hell, if he has it, it's not likely he'd even live as far as 77. The average age a CFer lives these days is only 35.
But let's assume he does, so I can answer your other questions. CF makes the mucus in your body, everywhere, thicker and stickier. It makes it harder to cough up, and invites infection in with enthusiasm. As far as what you can do, there's a lot. There are all sorts of meds out there, oral meds, inhaled meds, nebulized meds, IV meds, etc. Last ditch efforts for CFers usually is a double-lung transplant. If he actually has CF, he'll probably die from it, yes. And I know this doesn't help how you feel, but the fact that he's lived to 77 is a damn miracle. We lose babies, children, and young adults all the time. It does not go away, it's genetic, if you have it, you're stuck with it permanently. There's no cure.
If you have more basic questions, there's a lot of info right on this site:
<a target=new class=ftalternatingbarlinklarge href="http://cysticfibrosis.com/
">http://cysticfibrosis.com/
</a>As well as on:
<a target=new class=ftalternatingbarlinklarge href="http://www.cff.org/home/
">http://www.cff.org/home/
</a>Try those out.